Films for reproducing digitally stored medical diagnostic images and integrating non-image information

ABSTRACT

A radiation-sensitive silver halide film for reproducing digitally stored medical diagnostic images through a series of laterally offset exposures by a controlled radiation source followed by processing in 90 seconds or less, including development, fixing and drying. The film exhibits an average contrast in the range of from 1.5 to 2.0, measured over a density above fog of from 0.25 to 2.0. An emulsion layer is provided in which silver bromochloride grains (a) comprised of at least 10 mole percent bromide, based on silver, (b) having a mean equivalent circular diameter of less than 0.40 μm, (c) exhibiting an average aspect ratio of less than 1.3, and (d) coated at a silver coverage of less than 40 mg/dm 2 . Adsorbed to the surfaces of the silver bromochloride grains at least one spectral sensitizing dye having an absorption half peak bandwidth in the spectral region of exposure by the controlled exposure source. The film contains an infrared opacifying dye that is capable of reducing specular transmission through the film before, during and after processing to less than 50 percent, measured at a wavelength within the spectral region of from 850 to 1100 nm. The film contains a magnetic recording layer which provides a positive b* value influence that is more than offset by the negative b* value influence of the silver bromochloride emulsion, allowing magnetic recording layer integration into the film while achieving favorable image tone and minimum density characteristics.

FIELD OF THE INVENTION

The invention is directed to silver halide containing films forreproducing digitally stored medical diagnostic images.

DEFINITION OF TERMS

In referring to grains or emulsions containing two or more halides, thehalides are named in order of ascending concentrations.

The "aspect ratio" of a grain is the ratio of its equivalent circulardiameter (ECD) to its thickness. The ECD of a grain is the diameter of acircle having an area equal to the projected area of the grain.

The "coefficient of variation" (COV) of grain size (ECD) is defined as100 times the standard deviation of grain size divided by mean grainsize.

The term "covering power" is used to indicate 100 times maximum densitydivided by silver coating coverage measured in g/dm².

The term "cold" in referring to image tone is used to mean an image tonethat has a CIELAB b* value measured at a density of 1.0 above minimumdensity that is -6.5 or more negative. Measurement technique isdescribed by Billmeyer and Saltzman, Principles of Color Technology, 2ndEd., Wiley, New York, 1981, at Chapter 3. The b* values describe theyellowness vs. blueness of an image with more positive values indicatinga tendency toward greater yellowness.

The term "rapid access processor" is employed to indicate a radiographicfilm processor that is capable of providing dry-to-dry processing in 90seconds or less. The term "dry-to-dry" is used to indicate theprocessing cycle that occurs between the time a dry, imagewise exposedelement enters a processor to the time it emerges, developed, fixed anddry.

The term "average contrast" is employed to indicate contrast measuredover the density range of from 0.25 to 2.0 above fog. Contrast is, ofcourse, the ratio of ΔD+Δlog E, where D is density and E is exposure inlux-seconds.

The term "high intensity reciprocity failure" (HIRF) is employed toindicate a progressive reduction in speeds observed at equal exposureswithin the range of exposure times of from 10⁻¹ to 10⁻⁹ second.

The "half peak absorption bandwidth" of a dye is the spectral range innm over which it exhibits a level of absorption equal to at least halfof its peak absorption (λ_(max)).

The term "thiaalkylene bis(quaternary ammonium) salt" is employed todescribe salts containing two ammonio groups joined through athiaalkylene linkage. Ammonio groups are those that contain at least oneof the following quaternary nitrogen atoms: ##STR1## A "thiaalkylene"linkage is an alkylene linkage including at least one divalent sulfuratom replacing a carbon.

Research Disclosure is published by Kenneth Mason Publications, Ltd.,Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England.

BACKGROUND

Roentgen discovered X-radiation by the inadvertent exposure of a silverhalide photographic element. In 1913 the Eastman Kodak Companyintroduced its first product specifically intended to be exposed byX-radiation. Silver halide radiographic elements account for theoverwhelming majority of medical diagnostic images.

The needs of medical diagnostic imaging have dictated the evolution ofsilver halide radiographic elements:

(1) The need to minimize patient exposure to X-radiation has led to theuse of the high speed silver bromide and iodobromide emulsions.

(2) The need to verify quickly that appropriate images have beenobtained for diagnostic purposes has led to the creation of films thatare compatible with rapid access processors. Reductions in processingtimes to substantially less than 90 seconds are being vigorously pursuedin the art at this time.

(3) The fact that silver cannot be reclaimed (as is customary in colorphotography, for instance) has led to film constructions that maximizesilver covering power.

(4) The need to produce images for medical diagnoses that have similarand familiar qualities to aid the radiologist's diagnosis, includingfeatures, such as image tone, that go more to image appearance thanactual information content.

In recent years a number of alternative approaches to medical diagnosticimaging, particularly image acquisition, have become prominent. Medicaldiagnostic devices such as storage phosphor screens, CAT scanners,magnetic resonance imagers (MRI), and ultrasound imagers allowinformation to be obtained and stored in digital form. Althoughdigitally stored images can be viewed and manipulated on a cathode raytube (CRT) monitor, a hard copy of the image is almost always needed.

The most common approach for creating a hard copy of a digitally storedimage is to expose a radiation-sensitive silver halide film through aseries of laterally offset exposures using a laser, a light emittingdiode (LED) or a light bar (a linear series of independently addressableLED's). The image is recreated as a series of laterally offset pixels.Initially the radiation-sensitive silver halide films were essentiallythe same films used for radiographic imaging, except that finer silverhalide grains were substituted to minimize noise (granularity). Theadvantages of using modified radiographic films to provide a hard copyof the digitally stored image are that medical imaging centers arealready equipped to process radiographic films and are familiar withtheir image characteristics.

A typical film, Kodak Ektascan HN™, for creating a hard copy of adigitally stored medical diagnostic image includes an emulsion layercoated on a clear or blue tinted polyester film support. The emulsionlayer contains a red-sensitized silver iodobromide (2.5M % I, based onAg) cubic grain (0.33 μm ECD) emulsion coated at a silver coverage of 30mg/dm². A conventional gelatin overcoat is coated over the emulsionlayer. On the back side of the support a pelloid layer containing ared-absorbing antihalation dye is coated. A gelatin interlayer, used asa hardener incorporation site, overlies the pelloid layer, and a gelatinovercoat containing an antistat overlies the interlayer. Developedsilver is relied upon to provide in the infrared density required toactivate processor sensors. No dye is introduced for the purpose ofincreasing infrared absorption.

It is the prevailing practice to process radiographic films and the filmdescribed above in 90 seconds or less. For example, the Kodak X-OMAT 480RA™ rapid access processor employs the following processing cycle:

    ______________________________________                                        Development       24 seconds at 35° C.                                 Fixing            20 seconds at 35° C.                                 Washing           20 seconds at 35° C.                                 Drying            20 seconds at 65° C.                                 ______________________________________                                    

with up to 6 seconds being taken up in film transport between processingsteps.

A typical developer (hereinafter referred to as Developer A) exhibitsthe following composition:

    ______________________________________                                        Hydroquinone       30         g                                               Phenidone ™     1.5        g                                               KOH                21         g                                               NaHCO.sub.3        7.5        g                                               K.sub.2 SO.sub.3   44.2       g                                               Na.sub.2 S.sub.2 O.sub.3                                                                         12.6       g                                               NaBr               35.0       g                                               5-Methylbenzotriazole                                                                            0.06       g                                               Glutaraldehyde     4.9        g                                               Water to 1 liter/pH 10.0                                                      ______________________________________                                    

A typical fixer exhibits the following composition:

    ______________________________________                                        Sodium thiosulfate, 60%                                                                           260.0 g                                                   Sodium bisulfite    180.0 g                                                   Boric acid           25.0 g                                                   Acetic acid          10.0 g                                                   Water to 1 liter/pH 3.9-4.5                                                   ______________________________________                                    

Radiographic film processors such as RA 480 are capable of exposinglarge amounts of film over extended periods of time (e.g., a month ormore) before its processing solutions are drained and replaced. Extendeduse of the processing solutions is made possible by the addition ofsmall amounts of developer and fixer replenishers as each film isprocessed to compensate for developer and fixer losses by evaporationand film pick up.

Magnetic recording materials for incorporation in photographic elementsare disclosed in Research Disclosure, Vol. 365, September 1994, Item36544, Section XIV. Scan facilitating features, paragraph (2).

RELATED PATENT APPLICATIONS

Nair et at U.S. Ser. No. 08/604,272, filed Feb. 21, 1996, commonlyassigned, titled PHOTOGRAPHIC ELEMENTS CONTAINING A TRANSPARENT MAGNETICRECORDING LAYER, discloses a photographic sheet element comprising afilm support, coated on one side of the support a first hydrophiliccolloid layer unit having a thickness T_(E) and including a silverhalide emulsion layer, coated on the opposite side of the support asecond hydrophilic colloid layer unit including a transparent magneticrecording layer comprising ferromagnetic particles in a hydrophiliccolloid, the thickness of the transparent magnetic recording layer beingT_(M), and, coated between the support and the transparent magneticrecording layer a hydrophilic colloid pelloid layer, the thickness ofthe pelloid layer being T_(C). The relative thickness of the layersbeing represented by the formula: (T_(C) +T_(M))+T_(E) =>0 and <10.

Dickerson et al U.S. Ser. No. 08/574,508, filed concurrently herewithand commonly assigned, discloses a radiation-sensitive film forreproducing digitally stored medical diagnostic images through a seriesof laterally offset exposures by a controlled radiation source followedby processing in 90 seconds or less including development, fixing anddrying is disclosed. The film exhibits an average contrast in the rangeof from 1.5 to 2.0, measured over a density above fog of from 0.25 to2.0. An emulsion is provided in which silver bromochloride grainsprovided (a) containing at least 10 mole percent bromide, based onsilver, (b) having a mean equivalent circular diameter of less than 0.40μm, (c) exhibiting an average aspect ratio of less than 1.3, and (d)coated at a silver coverage of less than 40 mg/dm². Adsorbed to thesurfaces of the silver bromochloride grains is at least one spectralsensitizing dye having an absorption half peak bandwidth in the spectralregion of exposure by the controlled exposure source. The film alsocontains an infrared opacifying dye capable of reducing speculartransmission through the film before, during and after processing toless than 50 percent, measured at a wavelength within the spectralregion of from 850 to 1100 nm.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a film for reproducingdigitally stored medical diagnostic images that is capable ofadditionally providing non-image information in a separate record. It isa specific discovery of this invention that acceptably cold image tonescan be retained while employing a magnetic recording layer for providingnon-image information. The advantages of incorporating in a filmnon-image information is that this avoids the liability of keeping aseparate record correlated with the film. For example, if information onthe acquisition or processing of a film cannot be correlated to a filmimage, the value of the image is either compromised or lost entirely. Atpresent a radiologist will often read a film and simultaneously describethe critical features of the image on which a medical diagnosis isbased. The present invention by integrating a non-image record with theimage bearing film allows the medical diagnosis to be integrated withthe film, thereby essentially eliminating the burden of correlation andthe risk of inadvertent separation or loss of the film interpretation.

One of the surprising features of the invention is that it has beenpossible to integrate a magnetic recording layer (known to impart warmimage tones) for providing a non-image information record while stillretaining a relatively cold image tone, consistent with the image tonesof medical diagnostic radiographic films. A conventional practice is toincorporate a blue dye in a film (usually the support) to shift imagetone to colder values. Unfortunately, the blue dye addition increasesthe neutral minimum density of the film. As the film is constructed ofcomponents that produce progressively warmer image tones compensationwith blue dye becomes progressively less feasible, since the minimumdensity of the film is being degraded. Hence, the present inventionallows relatively colder image tones to be achieved without dyeincorporation and allows cold image tones to be realized with minimalblue dye incorporation.

It is an additional discovery of the invention that elements employingless than 40 mg/dm² silver can be constructed to satisfy image tonerequirements while also allowing more rapid processing and retainingcompatibility with rapid access processor sensors that depend on sensinginfrared density to control the processor.

The films of the invention consume lower amounts of developer than thefilms now in use commercially. This allows the operators of rapid accessprocessing equipment to reduce the amount of replenisher used duringprocessing and/or to increase the interval between developer solutionreplacement. This translates into less spent processing solutionrequiring disposal and less rapid access processor down time forservicing.

In one aspect the invention is directed to a radiation-sensitive silverhalide film for reproducing digitally stored medical diagnostic imagesthrough a series of laterally offset exposures by a controlled radiationsource followed by processing in 90 seconds or less, includingdevelopment, fixing and drying, comprised of a transparent film supporthaving front and back major faces, a front hydrophilic colloid layerunit containing an emulsion layer coated on the front face of thesupport, and a back hydrophilic colloid layer unit coated on the backface of the support, wherein (A) the film exhibits an average contrastin the range of from 1.5 to 2.0, measured over a density above fog offrom 0.25 to 2.0, (B) the emulsion layer (1) contains silverbromochloride grains (a) comprised of at least 10 mole percent bromide,based on silver, (b) having a mean equivalent circular diameter of lessthan 0.40 μm, (c) exhibiting an average aspect ratio of less than 1.3,and (d) coated at a silver coverage of less than 40 mg/dm², and (2) hasadsorbed to the surfaces of the silver bromochloride grains at least onespectral sensitizing dye having an absorption half peak bandwidth in thespectral region of exposure by the controlled exposure source, (C) theback hydrophilic colloid layer unit contains a magnetic recording layer,and (D) the film contains an infrared opacifying dye that is capable ofreducing specular transmission through the film before, during and afterprocessing to less than 50 percent, measured at a wavelength within thespectral region of from 850 to 1100 nm.

DESCRIPTION OF PREFERRED EMBODIMENTS

A typical film satisfying the requirements of the invention exhibits thefollowing structure:

    ______________________________________                                        SURFACE OVERCOAT (SOC-1)                                                      INTERLAYER (IL-1)                                                             EMULSION LAYER (EL)                                                           SUBBING LAYER (SL)                                                            TRANSPARENT FILM (TF)                                                         SUBBING LAYER (SL)                                                            PELLOID (PL)                                                                  MAGNETIC RECORDING LAYER (MRL)                                                SURFACE OVERCOAT (SOC-2)                                                      (I)                                                                           ______________________________________                                    

SL and TF together form a transparent film support. While a support inits simplest form can consist of any flexible transparent film, it iscommon practice to modify the surfaces of photographic and radiographicfilm supports by providing subbing layers to promote the adhesion ofhydrophilic colloids to the support. Although any conventionalphotographic film support can be employed, it is preferred to employ aradiographic film support, since this maximizes compatibility with therapid access radiographic film processors in which the films of theinvention are intended to be processed and provides a radiographic filmlook and feel to the processed film. Radiographic film supports usuallyexhibit these specific features: (1) the film support is constructed ofpolyesters to maximize dimensional integrity rather than employingcellulose acetate supports as are most commonly employed in photographicelements and (2) the film supports are blue tinted to contribute thecold (blue-black) image tone sought in the fully processed films,whereas photographic films rarely, if ever, employ blue tinted supports.Radiographic film supports, including the incorporated blue dyes thatcontribute to cold image tones, are described in Research Disclosure,Item 18431, cited above, Section XII. Film Supports. ResearchDisclosure, Vol. 365, September 1994, Item 36544, Section XV. Supports,illustrates in paragraph (2) suitable subbing layers to facilitateadhesion of hydrophilic colloids to the support. Although the types oftransparent films set out in Section XV, paragraphs (4), (7) and (9) arecontemplated, due to their superior dimensional stability, thetransparent films preferred are polyester films, illustrated in SectionXV, paragraph (8). Poly(ethylene terephthalate) and poly(ethylenenaphthenate) are specifically preferred polyester film supports.

SOC-1, IL-1 and EL together form a first processing solution permeablelayer unit. PL, MRL and SOC-2 together form a second processing solutionpermeable layer unit. Of all the layers in both layer units only theemulsion layer EL and the magnetic recording layer MRL are essential tothe practice of the invention. One function of the second layer unit isto balance the forces exerted by the first layer unit that wouldotherwise cause the film to curl. The ratio of hydrophilic colloid inthe first and second units is in all instances ≦0.1 and <100, preferablyfrom ≧0.2 to ≦1.0, optimally from ≧0.67 to ≦0.8. The anticurl functionis primarily performed by the pelloid layer PL. The pelloid alsoprovides a convenient site for dyes that are not required to interactwith the emulsion layer EL. For example the pelloid layer is a preferredlocation for an antihalation dye. The other layers are provided toenhance the physical handling characteristics of the element and toprovide convenient sites for modifying addenda.

In the simple, illustrative form shown film I contains a single emulsionlayer EL. The emulsion grains have been chosen to offer a particularlyadvantageous combination of properties:

(1) Rapid processing, allowing compatibility with rapid accessprocessors (including those having dry-to-dry processing in less than 40seconds) used for radio-graphic films;

(2) High covering power, allowing low silver coating coverages; and

(3) Enhanced image tone properties--that is, lower b* values when coatedin films lacking blue dye incorporation and cold image tones with lowerminimum densities when coated in films containing blue dye.

These properties are in part achieved by choosing emulsions containingsilver bromochloride grains. Since the emulsions are intended to beexposed by a controlled radiation source, typically a laser, a slightincrease in imaging speed that might be gained by iodide incorporationoffers little or no practical benefit and is, in fact, a significantdisadvantage when the reduction of development and fixing rates producedby iodide incorporation are taken into consideration. Iodide alsocontributes to warmer image tone. Thus, the grains as contemplated foruse are substantially free of iodide.

The grains contain at least 50 mole percent chloride. It is known thatsilver chloride exhibits a higher level of solubility than otherphotographic halides and hence the fastest development and fixing rates.While this might suggest the use of pure silver chloride emulsions inthe invention, this silver halide selection is not contemplated, sincepure silver chloride emulsions have been observed to exhibit much lowercovering power than the silver bromide and iodobromide emulsionsconventionally employed in radiographic elements.

It has been discovered that, if at least about 10 mole percent bromide,based on total silver, is incorporated into the emulsion grains,covering power is increased to approximately the higher covering powerlevels of silver bromide, most commonly used in radiographic films. Thegrains preferably contain from about 20 to 40 mole percent bromide,based on total silver contained in the grains.

Bromide incorporated in the grains to increase covering power alsoshifts image tones; however, the emulsions retain the slightly negativeb* values that are customarily sought for radiographic element images.

In addition to selecting the halide composition of the grains, the sizeof the grains is limited to increase the rate at which processing canoccur. Specifically, it is contemplated to limit the average ECD of thegrains to less than 0.40 μm. Preferably the emulsions are fine grainemulsions having mean grain ECD's in the range of from about 0.1 to 0.4μm. For such fine grain emulsions nontabular grain populations arepreferred. The average aspect ratio of a cubic grain emulsion is about1.1. In the emulsions of the invention average aspect ratios of lessthan 1.3 are contemplated. The nontabular grains can take any convenientconventional shape consistent with the stated average aspect ratio. Thegrains can take regular shapes, such as cubic, octahedral orcubo-octahedral (i.e., tetradecahedral) grains, or the grains can othershapes attributable to ripening, twinning, screw dislocations, etc.Preferred grains are those bounded primarily by {100} crystal faces,since {100} grain faces are exceptionally stable.

The fine grain emulsions of the invention offer a relatively high ratioof surface area to grain volume and hence are particularly suited forrapid access processing. A common alternative approach for achievinghigh surface area to volume grain ratios is to employ a thin or highaverage aspect ratio tabular grain emulsion. A significant advantage ofthe fine grain emulsions contemplated for use over tabular grainemulsions and other larger grain size emulsions is that lower grain sizedispersities are readily realized. Specifically, in the preferredemulsions of the invention the COV of the emulsions is less than 20percent and, optimally, less than 10 percent.

Lower grain dispersities allow more efficient silver utilization in thata higher percentage of the total grain population can achieve nearoptimum sensitization. This in turn facilitates achieving optimumcontrast ranges for digitally stored image reproduction. Blending ofemulsions of different mean grain sizes can be used to fine tunecontrast levels. It is specifically contemplated that the elements ofthe invention exhibit an average contrast in the range of from 1.5 to2.0. Both the blending of emulsions and the coating of emulsions inseparate superimposed layers are well known, as illustrated by ResearchDisclosure, Item 36544, I. Emulsion grains and their preparation, E.Blends, layers and performance categories, paragraphs (1), (2), (6) and(7).

The high covering power of the silver bromochloride grains allowscoating coverages to be maintained at less than 40 (preferably less than25) mg/dm², based on silver. Coating coverages for highly monodisperseemulsions as low as about 10 (preferably about 15) mg/dm² arecontemplated.

The silver bromochloride emulsions can be selected from amongconventional emulsions. A general description of silver halide emulsionscan be found in Research Disclosure, Item 36544, I. Emulsion grains andtheir preparation. The most highly monodisperse (lowest COV) emulsionsare those prepared by a batch double-jet precipitation process. It isnoted that high (>50 mole percent) chloride emulsions containing minoramounts of bromide otherwise satisfying the grain requirements of thisinvention are commonly used for preparing photographic reflectionprints. Specific examples of these emulsions are provided Hasebe et alU.S. Pat. No. 4,865,962, Suzumoto et al U.S. Pat. No. 5,252,454, andOshima et al U.S. Pat. No. 5,252,456, the disclosures of which are hereincorporated by reference. The silver bromochloride grains ofconventional high chloride emulsions intended for graphic artsapplications are also well suited for use in the present invention.Although reflection print and graphic arts emulsions overlap the bromideconcentration ranges of this invention, less than optimum bromide levelsfor this invention are preferred for those applications; however, onlyroutine adjustments during precipitation are needed to realize thepreferred silver bromochloride compositions of this invention. Generallyany convenient distribution bromide and chloride ions within the grainscan be employed in the practice of the invention. It is generallypreferred, based on convenience of preparation, to distribute bromideuniformly within the grains. Alternatively, silver bromide can beepitaxially deposited onto host grains containing lower levels of silverbromide (e.g., silver chloride host grains). The latter has theadvantage of allowing the silver bromide epitaxy to act as a sensitizer.

In the course of grain precipitation one or more dopants (grainocclusions other than silver and halide) can be introduced to modifygrain properties. For example, any of the various conventional dopantsdisclosed in Research Disclosure, Item 36544, Section I. Emulsion grainsand their preparation, sub-section G. Grain modifying conditions andadjustments, paragraphs (3), (4) and (5), can be present in theemulsions of the invention. In addition it is specifically contemplatedto dope the grains with transition metal hexacoordination complexescontaining one or more organic ligands, as taught by, Olm et al U.S.Pat. No. 5,360,712, the disclosure of which is here incorporated byreference. Dopants for increasing imaging speed by providing shallowelectron trapping sites (i.e, SET dopants) are the specific subjectmatter of Research Disclosure, Vol. 367, November 1994, item 36736.

Since the controlled radiation sources used to reproduce digitallystored images frequently employ short (<10⁻¹ second) exposure times andlaser exposures in fractional microseconds are common, it isspecifically contemplated to reduce high intensity reciprocity failure(HIRF) by the incorporation of iridium as a dopant. To be effective forreciprocity improvement the Ir must be incorporated within the grainstructure. To insure total incorporation it is preferred that Ir dopantintroduction be complete by the time 99 percent of the total silver hasbeen precipitated. For reciprocity improvement the Ir dopant can bepresent at any location within the grain structure. A preferred locationwithin the grain structure for Ir dopants to produce reciprocityimprovement is in the region of the grains formed after the first 60percent and before the final 1 percent (most preferably before the final3 percent) of total silver forming the grains has been precipitated. Thedopant can be introduced all at once or run into the reaction vesselover a period of time while grain precipitation is continuing. Generallyreciprocity improving non-SET Ir dopants are contemplated to beincorporated at their lowest effective concentrations. The reason forthis is that these dopants form deep electron traps and are capable ofdecreasing grain sensitivity if employed in relatively highconcentrations. These non-SET Ir dopants are preferably incorporated inconcentrations of at least 1×10⁻⁹ mole per silver up to 1×10⁻⁶ mole persilver mole. However, when the Ir dopant is in the form of ahexacoordination complex capable of additionally acting as a SET dopant,concentrations of up to about 5×10⁻⁴ mole per silver, are contemplated.Specific illustrations of useful Ir dopants contemplated for reciprocityfailure reduction are provided by B. H. Carroll, "Iridium Sensitization:A Literature Review", Photographic Science and Engineering, Vol. 24, No.6 November/December 1980, pp. 265-267; Iwaosa et at U.S. Pat. No.3,901,711; Grzeskowiak et al U.S. Pat. No. 4,828,962; Kim U.S. Pat. No.4,997,751; Maekawa et al U.S. Pat. No. 5,134,060; Kawai et al U.S. Pat.No. 5,164,292; and Asami U.S. Pat. Nos. 5,166,044 and 5,204,234.

The contrast of the silver bromochloride emulsions can be increased bydoping the with a hexacoordination complex containing a nitrosyl (NO) orthionitrosyl (NS) ligand. Preferred coordination complexes of this typeare disclosed by McDugle et al U.S. Pat. No. 4,933,272, the disclosureof which is here incorporated by reference.

The contrast increasing dopants (hereinafter also referred to as NO orNS dopants) can be incorporated in the grain structure at any convenientlocation. However, if the NO or NS dopant is present at the surface ofthe grain, it can reduce the sensitivity of the grains. It is thereforepreferred that the NO or NS dopants be located in the grain so that theyare separated from the grain surface by at least 1 percent (mostpreferably at least 3 percent) of the total silver precipitated informing the silver iodochloride grains. Preferred contrast enhancingconcentrations of the NO or NS dopants range from 1×10⁻¹¹ to 4×10⁻⁸ moleper silver mole, with specifically preferred concentrations being in therange from 10⁻¹⁰ to 10⁻⁸ mole per silver mole.

Combinations of Ir dopants and NO or NS dopants are specificallycontemplated. Where the Ir dopant is not itself a SET dopant, it isspecifically contemplated to employ non-SET Ir dopants in combinationwith SET dopants. Where a combination of SET, non-SET Ir and NO or NSdopants are employed, it is preferred to introduce the NO or NS dopantfirst during precipitation, followed by the SET dopant, followed by thenon-SET Ir dopant.

After precipitation and before chemical sensitization the emulsions canbe washed by any convenient conventional technique. Conventional washingtechniques are disclosed by Research Disclosure, Item 36544, citedabove, Section III. Emulsion washing.

The emulsions can be chemically sensitized by any convenientconventional technique. Such techniques are illustrated by ResearchDisclosure, Item 36544, IV. Chemical sensitization. Sulfur and goldsensitizations are specifically contemplated.

Since silver bromochloride emulsions possess little native sensitivitybeyond the ultraviolet region of the spectrum and controlled radiationsources used for exposure, such as lasers and LED's, are most readilyconstructed to provide exposures in the longer wavelength portions ofthe visible spectrum (e.g., longer than 550 nm) as well as the nearinfrared, it is specifically contemplated that one or more spectralsensitizing dyes will be absorbed to the surfaces of the silverchlorobromide grains. Ideally the maximum absorption of the spectralsensitizing dye is matched (e.g., within ±10 nm) to the exposurewavelength of the controlled exposure source. In practice any spectralsensitizing dye can be employed which, as coated, exhibits a half peakabsorption bandwidth that overlaps the spectral region of exposure bythe controlled exposure source.

A wide variety of conventional spectral sensitizing dyes are knownhaving absorption maxima extending throughout the visible and nearinfrared regions of the spectrum. Specific illustrations of conventionalspectral sensitizing dyes is provided by Research Diclsure, Item 18431,Section X. Spectral Sensitization, and Item 36544, Section V. Spectralsensitization and desensitization, A. Sensitizing dyes.

Since solid-state controlled exposure sources tend to be more efficientat longer wavelengths of emission, it might seem most advantageous tosensitize the silver bromochloride grains to the near infrared region ofthe spectrum. Instead, the best matches of photographic and controlledexposure sources is found in the red region of the spectrum. In thewavelength range of from about 633 to 690 nm there are a variety ofpopular controlled exposure sources in widespread use, includinghelium-neon lasers. It is generally realized that as the peak absorptionof spectral sensitizing dyes is shifted toward progressively longerwavelengths the propensity for dye-desensitization is increased.Dye-desensitization is inferred from the speed of an emulsion whensensitized to a particular wavelength is observed to be less than wouldbe expected based on native sensitivity or sensitization with anotherdye with a similar or shorter maximum absorption wavelength. Anabundance of spectral sensitizing dyes with low dye-desensitizationcharacteristics with peak absorptions in the red region of the spectrumand controlled exposure sources with emissions in the red region of thespectrum renders this a preferred combination for most imagingapplications. Of course, as better controlled exposure sources aredeveloped emitting at shorter visible wavelengths are developed, thechoice of preferred spectral sensitizing dyes will similarly shift.

Instability which increases minimum density in negative-type emulsioncoatings (i.e., fog) can be protected against by incorporation ofstabilizers, antifoggants, antikinking agents, latent-image stabilizersand similar addenda in the emulsion and contiguous layers prior tocoating. Such addenda are illustrated by Research Disclosure, Item36544, Section VII. Antifoggants and stabilizers, and Item 18431,Section II. Emulsion Stabilizers, Antifoggants and Antikinking Agents.

The silver halide emulsion and other layers forming the processingsolution permeable layer units on opposite sides of the supportadditionally contain conventional hydrophilic colloid vehicles(peptizers and binders), typically gelatin or a gelatin derivative.Conventional vehicles and related layer features are disclosed inResearch Disclosure, Item 36544, II. Vehicles, vehicle extenders,vehicle-like addenda and vehicle related addenda. The emulsionsthemselves can contain peptizers of the type set out in II. above,paragraph A. Gelatin and hydrophilic colloid peptizers. The hydrophiliccolloid peptizers are also useful as binders and hence are commonlypresent in much higher concentrations than required to perform thepeptizing function alone. The vehicle extends also to materials that arenot themselves useful as peptizers. Such materials are described in II.above, C. Other vehicle components.

The elements of the invention are fully forehardened to facilitate rapidaccess processing. The use of any convenient conventional hardener iscontemplated. Such hardeners are described in II. above, B. Hardeners.

To facilitate rapid access processing it is contemplated to limit thevehicle coating coverages on each side of the support. To allowdry-to-dry processing in less than 90 seconds, each processing solutionpermeable layer unit must be fully forehardened and limited to ahydrophilic colloid coating coverage of less than 65 mg/dm², preferablyless than 45 mg/dm². By fully forehardened it is meant that noadditional hardening is required during processing.

The magnetic recording layer MRL can take the form of any conventionalprocessing solution permeable magnetic recording layer. Such layerconstructions are disclosed in Research Disclosure, Vol. 343, November1992, Item 34390. In addition to hydrophilic colloid the magneticrecording layer contains fine ferromagnetic powders, such as such asferromagnetic γ-iron oxides, cobalt surface-treated ferromagnetic ironoxides, cobalt-doped ferromagnetic iron oxides, cobalt containing Fe₂O₃, ferromagnetic magnetites, cobalt-containing ferromagneticmagnetites, ferromagnetic chromium dioxides, ferromagnetic metalpowders, ferromagnetic iron powders, ferromagnetic alloy powders and theclass of ferromagnetic ferrite powders including barium ferrites.Additionally, the above mentioned powder particles may be modified toprovide lower light extinction and scattering coefficients by providingthem with a shell, of at least the same volume as the magnetic core, ofa low refractive index material that has its refractive index lower thanthe transparent polymeric material used to form the magnetizable layer.Typical shell materials may include amorphous silica, vitreous silica,glass, calcium fluoride, magnesium fluoride, lithium fluoride,polytetrafluoroethelene and fluorinated resins. Examples of theferromagnetic alloy powders include those comprising at least 75% byweight of metals which comprise at least 80% by weight of at least oneferromagnetic metal alloy (such as Fe, Co, Ni, Fe--Co, Fe--Ni, Co--Ni,Co--Ni--Fe) and 20% or less of other components (such as Al, Si, S, Sc,Ti, V, Cr, Fin, Cu, Zn, Y, Mo, Rh, Re, Pd, Ag, Sn, B, Ba, Ta, W, Au, Hg,Pb, La, Ce, Pr, Nd, Te, and Bi). The ferromagnetic metals can contain asmall amount of water, a hydroxide or an oxide. In addition, magneticoxides with a thicker layer of lower refractive index oxide or othermaterial having a lower optical scattering cross section, such as taughtby James et al U.S. Pat. No. 5,252,441, can also be used.

The dispersion preferably contains magnetic particles which are acicularor needle like magnetic particles. The average length of these particlesalong the major axis preferably is less than about 0.3, more preferably,less than about 0.2 μm. The particles preferably exhibit an axial ratio,that is, a length to diameter thickness ratio of up to about 5 or 6to 1. Preferred particles have a specific surface area of at least 30 m²/g, more preferably of at least 40 m² /g. Typical acicular particles ofthis type include, for example, particles of ferri and ferro iron oxidessuch as γ-ferric oxide, complex oxides of iron and cobalt, variousferrites and metallic iron pigments. Alternatively, small tabularparticles such as barium ferrites and the like can be employed. Theparticles can be doped with one or more ions of a polyvalent metal suchas titanium, tin, cobalt, nickel, zinc, manganese, chromium, or the likeas is known in the art.

A preferred particle consists of Co surface treated γ-Fe₂ O₃ having aspecific surface area of at least 40 m² /g. Particles of this type arecommercially available and can be obtained from Toda Kogyo Corporationunder the trade names CSF 4085V2, CSF 4565V, CSF 4585V and CND 865V andare available on a production scale from Pfizer Pigments Inc. under thetrade designations RPX-4392, RPX-5003, RPX-5026 and RPX-5012. For goodmagnetic recording, the magnetic particles preferably exhibit coerciveforce above about 500 Oe and saturation magnetization above 70 emu/g.

MRL can be prepared by initially forming a concentrated dispersion ofthe magnetic particles in water together with a dispersant, preferablyone having an HLB number of at least 8, more preferably an amphipathicwater-dispersible or soluble polymeric dispersant, and milling theresulting mixture in a device such as a ball mill, a roll mill, a highspeed impeller mill, media mill, an attritor, a sand mill or the like asdescribed in Nair et al U.S. Pat. No. 5,457,012, the disclosure of whichis here incorporated by reference. Milling is continued for a sufficienttime to ensure that substantially no agglomerates of the magneticparticles remain.

The length of milling time required depends on the particular millingdevice used. In general, milling should be continued from about 0.5 toabout 8 hours, preferably from about 1 to about 4 hours.

The coating concentration of the magnetic particles in the magneticrecording layer can range from 0.1 to 10 mg/dm², preferably from about0.2 to 0.7 mg/dm². The magnetic particles account for from 1 to 10(preferably 2 to 5) percent of the total weight of the magneticrecording layer.

In addition to the magnetic particles and hydrophilic colloid it isadditionally common practice to include in magnetic recording layers,singly or in combination, abrasive particles, reinforcing fillers andtin oxide.

Examples of abrasive and/or reinforcing filler particles includenonmagnetic inorganic powders with a Mohs scale hardness of not lessthan 6. Specific examples are metal oxides such as α-alumina, γ-alumina,chromium oxide (e.g., Cr₂ O₃), iron oxide alpha (e.g., Fe₂ O₃), silicondioxide, alumino-silicate and titanium carbide; carbides such as siliconcarbide and titanium carbide; nitrides such as, silicon nitride,titanium nitride and diamond in fine powder. Alpha alumina and silicondioxide are the preferred abrasives in accordance with this invention.These can be pre-dispersed in water using the same dispersants asdescribed in this invention and then incorporated into the coatingcomposition.

Tin oxide particles in any form may be employed such as tin oxide per seor doped tin oxides, such as, antimony or indium doped tin oxide. Thetin oxide may be used in either the conductive or nonconductive form;however, when in the conductive form, an additional advantage is gainedin that the layer also acts as an antistat. Suitable conductiveparticles are disclosed in Kawaguchi et al U.S. Pat. Nos. 4,394,441 and4,418,141, Yoshizumi U.S. Pat. No. 4,431,764, Takimoto et al U.S. Pat.No. 4,495,276, and Bishop et al U.S. Pat. No. 4,990,276, the disclosuresof which are here incorporated by reference. Useful tin oxide particlesare commercially available from Keeling and Walker, Ltd. under the tradedesignation Stanostat CPM 375; DuPont Co. under the trade designationZelec-ECP 3005XC and 3010SC and Mitsubishi Metals Corp. under the tradedesignation T-1. Preferred metal antimonates include those having rutileor rutile-related crystallographic structures as those disclosed inChristian et al U.S. Pat. No. 5,368,995, the disclosure of which is hereincorporated by reference. These can be also be pre-dispersed in waterusing the same dispersants as described in this invention and thenincorporated into the coating composition.

The surface overcoats SOC-1 and SOC-2 are typically provided forphysical protection of the emulsion and pelloid layers. In addition tovehicle features discussed above the overcoats can contain variousaddenda to modify the physical properties of the overcoats. Such addendaare illustrated by Research Disclosure, Item 36544, IX. Coating physicalproperty modifying addenda, A. Coating aids, B. Plasticizers andlubricants, and D. Matting agents. The interlayer IL1 is typically athin hydrophilic colloid layer that provides a separation between theemulsion and the surface overcoat addenda. It is quite common to locatesurface overcoat addenda, particularly anti-matte particles, in thisinterlayer.

SOC-2, which overlies the MRL, comes into direct contact with themagnetic heads used for information transfer to and from the film. Forbest head performance it is specifically preferred to incorporate inSOC-2 a lubricant that will both minimize friction between the head andthe film and resist transfer to the head. The incorporation ofrelatively immobile organic lubricants into SOC-2 has been found to bewell suited for this purpose. By dispersing the lubricants in thehydrophilic colloid vehicle of the overcoat the overcoat remainsprocessing solution permeable. Examples of suitable relatively immobileorganic lubricants, sometimes referred to as waxes, include monobasicfatty acids having 10 to 40 carbon atoms (which may contain unsaturatedbonds or may be branched) and metal salts thereof (such as Li, Na, K andCu), monovalent, divalent, trivalent, tetravalent, pentavalent andhexavalent alcohols having 12 to 40 carbon atoms (which may containunsaturated bonds or may be branched), alkoxy alcohols having 12 to 40carbon atoms, mono-, di- and tri-esters of monobasic fatty acids having10 to 40 carbon atoms (which may contain unsaturated bonds or may bebranched) and one of monovalent, divalent, trivalent, tetravalent,pentavalent and hexavalent alcohols having 2 to 12 carbon atoms (whichmay contain unsaturated bonds or may be branched), fatty acid esters ofmonoalkyl ethers of alkylene oxide polymers, fatty acid amides having 8to 40 carbon atoms and aliphatic amines having 8 to 40 carbon atoms.Specific examples of these compounds (i.e., alcohols, acids or esters)include carnauba wax, lauric acid, myristic acid, palmitic acid, stearicacid, behenic acid, butyl stearate, oleic acid, linoleic acid, linolenicacid, elaidic acid, octyl stearate, amyl stearate, isooctyl stearate,octyl myristate, butoxyethyl stearate, anhydrosorbitan monostearate,anhydrosorbitan distearate, anhydrosorbitan tristearate, pentaerythrityltetrastearate, oleyl alcohol and lauryl alcohol.

The pelloid layer is a preferred location for antihalation dyes. Suchdyes are illustrated by Research Disclosure, Item 36544, Section VIII.Absorbing and scattering materials, B. Absorbing materials. Theantihalation dyes absorb light that has passed through the emulsionlayer to minimize light reflection and the associated reduction in imagesharpness. Antihalation dyes are chosen to be decolorized duringprocessing. Alternatively, anithalation dye can be coated in a separateprocessing solution permeable layer, not shown in Element I, interposedbetween the support and the emulsion layer.

When the pelloid layer does not contain an antihalation dye, there is noneed for processing solution to permeate PL, MRL and SOC-2. This allowshigher levels of hardening to minimize solution ingestion duringprocessing. Further, when processing solution permeation of these layersis not needed, a broader range of coating compositions, not limited tohydrophilic colloid vehicle coatings, are feasible in these layers.

Addenda to protect the elements from static discharge (i.e., antistats)can be incorporated in the elements of the invention at any convenientlocation. Antistats can be conveniently located in one or both of thesurface overcoats. Antistats that are compatible with the magneticrecording particles, such as tin oxide, described above, can be locatedin the magnetic recording layer. One preferred location for antistataddenda is in a separate coating, not shown, interposed between thesupport and the pelloid. Antistats are particularly useful in protectingthe elements from static discharge that can accumulate from repeatedreading of information contained in the magnetic recording layer and/orhigh speed transport of the film. Conventional antistats useful in theelements of the invention are disclosed in Research Disclosure, Item36544, IX. Coating physical property modifying addenda, C. Antistats.Any of the antistatic agents set forth in Sakakibara U.S. Pat. No.5,147,768, here incorporated by reference, can be employed. Preferredantistats include metal oxides, for example, tin oxide, antimony dopedtin oxide, vanadium pentoxide, and metal antimonates.

Although the silver chlorobromide emulsions described above provide anadvantageous combination of properties, both the choice of bromochloridecompositions and the limited silver coating coverages render theelements either incapable or only marginally capable of detection by theinfrared (IR) sensors typically contained in rapid access processors.That is, the emulsion layer, before or after processing, is incapable ofsignificantly attenuating IR radiation in the 850 to 1100 nm spectralregion. Customarily when a radiographic film is placed in a rapid accessprocessor the refractive indices mismatch of the silver halide grainsand the vehicle is relied upon to scatter an IR sensor beam directed atthe film. Silver bromochloride exhibits a lower refraction index thansilver bromide or iodobromide. A beam attenuation of at least 50 percentprovides a signal that a radiographic film has been placed in theprocessor. After the film has been processed, the developed silver in aconventional radiographic element is capable of providing the required50 percent attentuation of another, exit IR sensor. When the exit sensorbeam is no longer attenuated, this provides a signal to switch theprocessor to a shutoff or standby mode.

To render the element of the invention reliably detectable byconventional IR radiographic film entry and exit sensors in rapid accessprocessors, it is contemplated to incorporate in the element of theinvention an infrared opacifying dye capable of reducing speculartransmission through the element before, during and after processing toless than 50 percent (preferably less than 25 percent), measured at awavelength within the spectral region of from 850 to 1100 nm. Forexample, if the near IR sensors employ 920 nm lasers, the dye asincorporated in the cleaning element must reduce specular transmissionthrough the cleaning element at 920 nm to less than 50 percent and,preferably, less than 25 percent. Since the sensor beam is limited to920 nm wavelength radiation, the presence or absence of adsorption bythe dye at other wavelengths is immaterial. The most efficient infraredopacifying dye choice would be a dye having a maximum absorption at(i.e., within ±10 nm) the wavelength of the sensor beams. Dyes havinghalf peak absorption bandwidths that overlap the wavelength of thesensor beams are practically acceptable choices.

The infrared opacifying dye can be located within the element at anyconvenient location. It can be incorporated in the support (e.g., in thetransparent film TF or in one or both of the subbing layers SL), coatedon the support in any one or combination of the processing solutionpermeable layers. The preferred location for the infrared opacifying dyeis in the pelloid layer PL.

When the infrared opacifying dye is added in one or more layerspenetrated by processing solutions, the dye as coated must be waterinsoluble. Thus, for coating in this location infrared opacifying dyesare preferred that are water insoluble or that are capable of forming awater insoluble complex as coated. For example, the dye may form a waterinsoluble complex with gelatin. The dye can be added to hydrophiliccolloid vehicle forming the layer in a water miscible solvent, such asmethanol. Alternatively the dye can be added to the hydrophilic colloidin the form of solid dye particles. The maximum size of the dyeparticles is limited only by coating convenience. Preferably the dyeparticles have a mean size of less than 100 micrometers.

The infrared opacifying dyes can be selected from among conventionaldyes known to exhibit a half peak bandwidth that is at least partiallylocated within the spectral region of from 850 to 1100 nm. Watersolubility can be reduced with little or no impact on absorption merelyby altering the choice of substituents. Generally ionic substituents,such as acidic groups, increase water solubility while nonpolar andparticularly higher molecular weight nonpolar substituents decreasewater insolubility.

Dyes in the cyanine dye class are preferred infrared opacifying dyes.These dyes contain an odd number of methine (--CH═) or substitutedmethine groups linking two basic nuclei. The synthesis of dyes in thecyanine dye class having the required absorption in the 850 to 1100 nmrange is particularly convenient, since the absorption of these dyes canbe extended to longer wavelengths merely by increasing the number ofmethine groups linking the two basic nuclei. In preferred steric formsthe dyes aggregate and exhibit bathochromically shifted absorptions.Generally absorption in the spectral region of from 850 to 1100 nm canbe realized when 7, 9 or 11 methine groups link the basic nuclei of acyanine dye. Such dyes are termed tricarbocyanine, tetracarbocyanine andpentacarbocyanine dyes, respectively. These methine linkages can be andare usually substituted. A very common substitution, often used topromote aggregation, is for the middle (meso) methine group to besubstituted. In a preferred dye selection the meso methine group and thetwo adjacent methine groups form part of a 5 or 6 membered ring.

Tricarbocyanine, tetracarbocyanine and pentacarbocyanine dyes areillustrated by Simpson et al U.S. Pat. No. 4,619,892, Parton et al U.S.Pat. Nos. 4,871,656, 4,975,362, 5,061,618 and 5,108,882, Davies et alU.S. Pat. No. 4,988,615, Friedrich et al U.S. Pat. No. 5,009,992,Muenter et al U.S. Pat. No. 5,013,642, and Hamer The Cyanine Dyes andRelated Compounds, Interscience, 1964, Chapters VIII and IX.

Particularly preferred infrared opacifying dyes are tricarbocyanine dyessatisfying the formula: ##STR2## where X₁ and X₂ each independentlyrepresent the atoms necessary to complete a nucleus that with (L--L)_(p)or (L═L)_(q) form a 5 or 6-membered heterocyclic nucleus;

n, p and q each independently represents 0 or 1;

each L independently represents a methine group;

L₁ and L₂ are substituted methine groups that together form a 5- or6-membered carbocyclic ring (that is, the methine carbon atoms arelinked by 1,2-ethylene or 1,3-propylene groups);

R₁ and R₂ each independently represents an alkyl, sulfoalkyl orcarboxyalkyl group (where the acid moieties can be present as a freeacid, salt or ester);

Y represents an amino or sulfonyl group;

the alkyl moieties contain in each instance from 1 to 6 carbon atoms;and

W is a counterion to balance the charge of the molecule.

When Y is a sulfonyl group, it is preferably an --SO₂ R₃ group, where R₃is an aliphatic hydrocarbon or aromatic hydrocarbon containing from 1 to10 carbon atoms. One or more heteroatoms (e.g., O, S, N) can besubstituted for carbon in the aromatic hydrocarbon moieties. In aspecifically preferred form R₃ is alkyl of from 1 to 6 carbon atoms.

When Y is an amino group, it can be a primary, secondary or tertiaryamino group. Amino substituents when present can be independentlyselected from among alkyl and aryl substituents, typically eachcontaining from 1 to 10 carbon atoms. Alternatively, when the amino is atertiary amino substituent, the substituents can together with the aminonitrogen form a five or six membered heterocyclic ring. Piperidino andpiperazino groups are preferred amino substituents.

Since the infrared opacifying dye remains a permanent part of theelement, it must be free of any objectionable visible color. In generalthe opacifying dyes are chosen to be substantially colorless to the eye(e.g., to exhibit an optical density of less than 0.1 in the visiblespectrum). However, opacifying dyes that appear blue can be employed, ifdesired, to replace the image tone controlling function of aconventional blue tinted support.

The following are illustrations of particularly preferred infraredopacifying dyes:

IROD-1Anhydro-3,3'-bis(3-sulfobutyl)-10,12-ethylene-11-[4-(N,N-dimethylthiocarbamoyl)1-piperazino]thiatricarbocyaninetriethylamine salt;

IROD-2Anhydro-3,3'-bis(3-sulfobutyl)-10,12-ethylene-11-[4-(N,N-dimethylsulfamoyl)-1-piperazino]thiatricarbocyaninetriethylamine salt;

IROD-3Anhydro-3,3'-bis(3-sulfopropyl)-10,12-ethylene-11-piperidinothiatricarbocyaninetriethylamine salt;

IROD-43,3'-Diethyl-10,12-ethylene-11-(4-methylpiperazino)thiatricarbocyanineperchlorate;

IROD-53,3'-Diethyl-10,12-ethylene-11-(2-methylpiperidino)thiatricarbocyanineperchlorate;

IROD-63,3'-Diethyl-10,12-ethylene-11-(2-methylpiperazino)benz[c]thiatricarbocyanineperchlorate;

IROD-7 3,3'-Diethyl-10,12-ethylene-11-diphenylaminothiatricarbocyanineperchlorate

IROD-8Anhydro-3,3'-bis(3-sulfopropyl)-10,12-ethylene-11-(N,N-diphenylamino)thiacarbocyaninehydroxide, triethylamine salt;

IROD-9Anhydro-3,3'-bis(3-sulfopropyl)-10,12-ethylene-11-(N-methyl-N-phenylaminothiacarbocyaninehydroxide, triethylamine salt;

IROD-103,3'-Diethyl-10,12-ethylene-11-(N,N-diphenylamino)benz[c]thiacarbocyanineperchlorate;

IROD-11Anhydro-3,3'-bis(3-sulfopropyl)-10,12-ethylene-11-(N,N-diphenylamino)benz[c]thiacarbocyaninehydroxide, triethylamine salt;

IROD-12Anhydro-3,3'-bis(3-sulfopropyl)-10,12-ethylene-11-(N-methyl-N-phenylamino)benz[c]thiacarbocyaninehydroxide, triethylamine salt;

IROD-13Anhydro-3,3'-bis(2-sulfoethyl)-12,14-propylene-13-methylsulfonyl-1,1,1',1'-tetramethylbenz[e]indolotricarbocyaninehydroxide, sodium salt;

IROD-14Anhydro-3,3'-bis(3-sulfopropyl)-12,14-propylene-13-methylsulfonyl-1,1,1',1'-tetramethylbenz[e]indolotricarbocyaninehydroxide, sodium salt;

IROD-15Anhydro-3,3'-bis(3-sulfobutyl)-13-methylsulfonyl-12,14-propylene-1,1,1',1'-tetramethylbenz[e]indolotricarbocyaninehydroxide, sodium salt;

IROD-16Anhydro-3,3'-bis(3-sulfobutyl)-13-methylsulfonyl-12,14-propylene-1,1,1',1'-tetramethylbenz[e]indolotricarbocyaninehydroxide, sodium salt;

IROD-17Anhydro-3,3'-bis(3-sulfopropyl)-12,14-ethylene-13-methylsulfonyl-1,1,1',1'-tetramethylbenz[e]indolotricarbocyaninehydroxide, sodium salt;

IROD-183,3'-Diethyl-11-ethylsulfo-10,12-propylenebenz[c]thiacarbocyanineperchlorate.

It has been discovered quite unexpectedly that an increase in imagingspeed can be realized by incorporating a thiaalkylene bis(quaternaryammonium) salt in at least one of (1) a hydrophilic colloid layer unitof the film or (2) the developer (or activator) solution used duringprocessing. The thiaalkylene bis(quaternary ammonium) salt acts as adevelopment accelerator and hence its activity is dependent upon beingpresent within the emulsion layer during development. When thethiaalkylene bis(quaternary ammonium) salt is incorporated in adeveloper or activator, a contemplated concentration of the developmentaccelerator is in the range of from 0.1 to 1.0 g/L, preferably from 0.2to 0.6 g/L.

A preferred location of the thiaalkylene bis(quaternary ammonium) saltis in the emulsion layer containing hydrophilic colloid layer unit.Processing solution permeates this entire layer unit during developmentand hence the thiaalkylene bis(quaternary ammonium) salt diffuses intothe emulsion layer with the developer or activator solution, if it isnot initially coated directly within the emulsion layer. Usefulthiaalkylene bis(quaternary ammonium) salt concentrations in thehydrophilic colloid layer unit containing the emulsion layer arecontemplated to range from 0.02 to 1.0 mg/dm², preferably from 0.05 to0.60 mg/dm².

When the thiaalkylene bis(quaternary ammonium) salt is incorporated in ahydrophilic colloid layer unit on the back side of the support, it isnecessary that the salt diffuse from the back side layer unit into thedeveloper and then into the hydrophilic colloid layer unit containingthe emulsion layer. In this instance somewhat higher concentrations arerequired than when the salt is incorporated directly in the emulsionlayer containing hydrophilic colloid layer unit to achieve comparativeeffects.

In a preferred form the thiaalkylene bis(quaternary ammonium) saltsatisfies the formula:

    Q.sup.1 --[(CH.sub.2).sub.n --S--].sub.m --(CH.sub.2).sub.p --Q.sup.2 X(III)

where

m is an integer of from 1 to 3,

n and p are independently integers of from 1 to 6,

Q¹ and Q² are ammonio groups, and

X represents the ion or ions necessary to provide charge neutrality.

Typical ammonio groups include simple acyclic groups, such asillustrated by the formula: ##STR3## where R¹, R² and R³ are independenthydrocarbon groups each containing from 1 to 10 (preferably 1 to 6)carbon atoms. To facilitate solubility and mobility in processingsolutions it is preferred to limit the number of carbon atoms or tosubstitute the hydrocarbon atoms with polar substituents, such ascarboxy, sulfonyl, carbamoyl, amido, sulfamoyl or sulfonamido groups.Preferred hydrocarbon groups are phenyl, alkylphenyl, phenylalkyl andalkyl groups. It is specifically preferred to limit the total number ofcarbon atoms in any one ammonio group to 10 or less.

In an alternative preferred form R¹ and R² can together complete amembered ring. Where R¹ and R² together form an alkylene group,typically the alkylene group contains from 4 to 10 carbon atoms. In mostinstances R¹ and R² are chosen to complete a 5 or 6 membered ring. Forexample, R¹ and R² can together complete an N-R³ -pyrrolio, N-R³-pyrrolinio, N-R³ -pyrazinio, N-R³ -morpholinio, N-³ -piperidinio or N-³-piperazinio ring.

It is specifically contemplated to employ ammonio groups illustrated bythe following formula: ##STR4## where R⁴ and R⁵ together complete a fiveor six membered ring. For example, the ammonio group can be anN-2H-pyrroleninio or N-pyridinio group.

In heterocyclic ammonio groups and particularly aromatic heterocylicammonio groups it is not necessary that the point of attachment to thelinking thiaalkylene group be at the site of the quaternized nitrogenatom. From example, ammonio groups such as 4-(N-methylpyrindinio) andN'-(N-methylpyrazinio) ammonio groups are specifically contemplated.

The charge balancing counterions can be chosen from any of the anionscommonly found in silver halide emulsion layers, including halide ions(e.g., fluoride, chloride, bromide), hydroxide, phosphate, sulfate,nitrate, tetrafluoroborate, p-toluenesulfonate, and perchlorate. Anionscompatible with silver halide emulsions can be used interchangeablywithout affecting the activity of the development accelerator.

The following are illustrations of specific thiaalkylene bis(quaternaryammonium) salts:

Q-1 N,N'-[1,8-(3,6-dithiaoctylene)]bis(1-methylpiperidinium)p-toluenesulfonate;

Q-2 N,N'-[1,10-(3,8-dithiadecylene)]bis(1-methylpiperidinium)p-toluenesulfonate;

Q-3 N,N'-[1,12-(3,10-dithiadodecylene)]bis(1-methylpiperidinium)p-toluenesulfonate;

Q-4 N,N'-[1,8-(3,6-dithiaoctylene)]bis(1-methylmorpholinium)p-toluenesulfonate;

Q-5 N,N'-[1,8-(3,6-dithiaoctylene)]bis(trimethylammonium)p-toluenesulfonate;

Q-6 N,N'-[1,8-(3,6-dithiaoctylene)]bis(diethylmethylammonium)p-toluenesulfonate;

Q-7 N,N'-[1,8-(3,6-dithiaoctylene)]bis(1,7-heptylenemethylammonium)p-toluenesulfonate;

Q-8 N,N'-[1,8-(3,6-dithiaoctylene)]bispyridinium tetrafluoroborate;

Q-9N,N'-[1,8-(3,6-dithiaoctylene)]bis(4-dimethylaminopyridinium)bromide;

Q-10 N,N'-[1,8-(3,6-dithiaoctylene)]bis(3-formylpyridinium)bromide;

Q-11 N,N'-[1,8-(3,6-dithiaoctylene)]bis(4-methylpyridinium)bromide;

Q-12N,N'-[1,8-(3,6-dithiaoctylene)]bis[3-(4-methylphenylsulfonamido)pyridinium]bromide;

Q-13 N,N'-[1,8-(3,6-dithiaoctylene)]bis[4-(5-nonyl)pyridinium)bromide;

Q-14 N,N'-[1,8-(3,6-dithiaoctylene)]bis(3-pentamido)pyridinium)bromide;

Q-15N,N'-[1,8-(3,6-dithiaoctylene)]bis(3-propylcarbamoyl)pyridinium)bromide;

Q-16 N,N'-[1,8-(3,6-dithiaoctylene)]bis(1-methylmorpholinium)p-toluenesulfonate;

Q-17N,N'-[1,13-(2,12-dihydroxy-3,6-dithiatridecylene)]bis(trimethylammonium)p-toluenesulfonate;

Q-18N,N'-[1,13-(2,12-dihydroxy-3,6-dithiatridecylene)]bis(dibutylmethylammonium)p-toluenesulfonate;

Q-19 4,4'-[1,11-(3,6,9-trithiaundecyl)]bis(N-methylpyridinium)p-toluenesulfonate;

Q-20N,N'-[1,11-(3,6,9-trithiaundecyl)]bis[4-(dimethylamino)pyridinium)bromide;

Q-21 4,4'-[1,8-(3,6-dithiaoctyl)]bis(N-methylpyridinium)perchlorate;

Q-22 2,2'-[1,8-(3,6-dithiaoctyl)]bis(N-methylpyridinium)perchlorate;

Q-23 N,N'-[1,19-(7,13-dithianonadecyl)]bis(2-methylpyridinium)p-toluenesulfonate;

Either or both of the hydrophilic colloid layer units coated on thefront and back sides of the support, but most preferably the hydrophiliccolloid layer unit containing the emulsion layer, can contain one ormore developing agents. It is generally known that developing agents canbe incorporated in a photographic or radiographic element and thatdevelopment can be initiated by bringing the element into contact withan activator solution--that is, a solution otherwise similar to adeveloper, but lacking a developing agent. The problem that haspreviously been encountered in relying entirely on the element to supplythe developing agent is that 1 equivalent of developing agent isrequired per mole of silver halide. Such large quantities ofincorporated developing agent degrade the physical handling propertiesof a conventional element.

In the present invention the limited concentrations of silver (<40mg/dm²) allow proportionately lower developing agent concentrations andhence reduce the negative impact of incorporated developing agent on thephysical handling properties of the elements of the invention. The useof a thiaalkylene bis(ammonium) salt of the type described above alsoallows the levels of incorporated developing agent to be reduced. It isalso contemplated to employ, either incorporated in the film or insolution, a supplemental developing agent that is capable of reducingthe incorporation of oxidized developing agent below 1 equivalent,preferably to 0.5 equivalent or less, and thereby allowing therestricted concentration developing agent to reduce larger amounts ofsilver halide than would be otherwise possible. When one or acombination of (a) lower silver coating coverages, (b) developmentaccelerator incorporation, and (c) supplemental developing agentincorporation, it is possible to rely entirely on developing agentincorporated in the film for development and hence employ an activatorsolution instead of a developer processing.

It is additionally recognized that the incorporation of developing agentneed not be at a sufficiently high level to replace completelydeveloping agent in the developer. For example, one specificallycontemplated function of incorporated developing agent can be to reducethe amount of developing agent that must be added to the developer inreplenisher additions. Lowered concentrations of developing agent and,preferably, the supplemental developing agent, are contemplated bothwith and without development accelerator incorporation.

The incorporated developing agents and supplement developing agents canbe of any conventional type, but are preferably of the types customarilyused with rapid access processors. Preferred incorporated developingagents are hydroquinones. The following are illustrations of typicalhydroquinone developers:

HQ-1 Hydroquinone;

HQ-2 Methylhydroquinone;

HQ-3 2,6-Dimethylhydroquinone;

HQ-4 Chlorohydroquinone;

HQ-5 2-Methyl-3-chlorohydroquinone;

HQ-6 Dichlorohydroquinone;

HQ-7 Bromohydroquinone;

HQ-9 Hydroxyhydroquinone;

HQ-10 Potassium hydroquinone sulfonate.

The supplemental developing agents are most typically p-aminophenols,p-phenylenediamines, reductones or 3-pyrazolidinones, with the latterbeing most widely used in rapid access processing. The following arespecific illustrations of supplemental developing agents:

SDA-1 p-Aminophenol;

SDA-2 p-Methylaminophenol;

SDA-3 p-Ethylaminophenol;

SDA-4 p-Dimethylaminophenol;

SDA-5 p-Dibutylaminophenol;

SDA-6 p-Piperidinophenol;

SDA-7 4-Dimethylamino-2,6-dimethoxyphenol;

SDA-8 N-Methyl-p-phenylenediamine;

SDA-9 N-Ethyl-p-phenylenediamine;

SDA-10 N,N-Dimethyl-p-phenylenediamine;

SDA-11 N,N-Diethyl-p-phenylenediamine;

SDA-12 N,N,N',N'-Tetramethyl-p-phenylenediamine;

SDA-13 4-Diethylamino-2,6-dimethoxyaniline;

SDA-14 Piperidino-hexose-reductone;

SDA-15 Pyrrolidino-hexose-reductone;

SDA-16 1-Phenyl-3-pyrazolidinone;

SDA-17 4,4-Dimethyl-1-phenyl-3-pyrazolidinone;

SDA-18 4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone;

SDA-19 4,4-Bis(hydroxymethyl)-1-phenyl-3-pyrazolidinone;

SDA-20 4,4-Dimethyl-1-tolyl-3-pyrazolidinone;

SDA-21 4,4-Dimethyl-1-xylyl-3-pyrazolidinone;

SDA-22 1,5-Diphenyl-3-pyrazolidinone.

EXAMPLES

The invention can be better appreciated by reference to the followingspecific embodiments. All coating coverages, indicated parenthetically,are in mg/dm², except as otherwise indicated. Silver halide coatingcoverages are reported in terms of silver.

Example 1

Two elements of the layer arrangement of Element I, described above,were provided, but with differing silver halide grain compositions. Theelements were constructed for exposure using a heliumneon 670 nm laser.

FILM SUPPORT

The film support was a conventional blue tinted 7 mil (177.8 mm)transparent poly(ethylene terephthalate) radiographic film support.

PELLOID

The pelloid contained gelatin (27.3) and the antihalation dyesbis[3-methyl-1-(p-sulfophenyl)-2-pyrazolin-5-one-(4)]pentamethineoxonol(0.96) and 1,4-benzene sulfonic acid,2-[3-acetyl-4-{5-[3-acetyl-1-(2,5-disulfophenyl)-1,5-dihydro-5-oxo-4H-pyrazol-4-ylidene]-1,3-pentadienyl}-5-hydroxy-1H-pyrazol-1-yl]pentasodiumsalt (1.74).

SURFACE OVERCOAT SOC-1

The surface overcoat contained gelatin (4.5), matte beads (0.21),silicone lubricant (0.14) and surfactant.

INTERLAYER IL-1

The interlayer contained gelatin (4.5).

EMULSION LAYER

The emulsion layer contained an emulsion comprised of sulfur and goldsensitized silver halide cubic grains (25.1) having a mean ECD of 0.26μm optimally spectrally sensitized withanhydro-9-ethyl-3,3'-bis(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyaninehydroxide, sodium salt; gelatin (25.1); 4-hydroxy-6-methyl-2-methylmercapto-1,3,3A-tetraazaindene (3 g/Ag M); resorcinol (1.0) andsodium disulfocatechol (0.19). The silver halide compositions are setout in Table I below.

MAGNETIC RECORDING LAYER MRL

The magnetic recording layer contained gelatin (11.1), Sumitomo-AKP-50™alumina abrasive(0.6), Toda CF-4085V2™ Fe₂ O₃ (0.6), and polystyrenesulfonate, sodium salt (0.13).

SURFACE OVERCOAT SOC-2

The surface overcoat contained gelatin (0.82), carnuba wax (1.9) andpolystyrene sulfonate, sodium salt (0.065).

All of the hydrophilic colloid layers were fully forehardened using 5.0wt % bis(vinylsulfonylmethyl)ether, based on the weight of gelatin.

Two variations of the two elements above were constructed, but with themagnetic recording layer MRL and SOC-2 replaced with a gelatininterlayer identical to IL-1 and a conventional surface overcoat of thefollowing composition: gelatin (4.5), matte beads (0.29), siliconelubricant (0.12), surfactant and the antistats lithium trifluoromethane(0.76) and Zonyl FSN™ (0.38), F(CF₂ CF₂)₃₋₈ CH₂ CH₂ O--(CH₂ CH₂ O )₈₋₁₂H.

Exposure and Processing

The elements were exposed using a helium-neon laser emitting at 670 nm.Processing was conducted using a Kodak X-OMAT M6A-N™ processor, usingthe processing cycle, developer and fixer, previously described inconnection with processor Kodak X-OMAT 480 RA™.

                  TABLE I                                                         ______________________________________                                        Silver Halide (mol. ratio)                                                                      MRL     Image Tone (b*)                                     ______________________________________                                        Br.sub.0.30 Cl.sub.0.70                                                                         No      -12.6                                               I.sub.0.03 Br.sub.0.97                                                                          No       -8.8                                               Br.sub.0.30 Cl.sub.0.70                                                                         Yes     -11.6                                               I.sub.0.03 Br.sub.0.97                                                                          Yes      -7.7                                               ______________________________________                                    

By comparing the b* value of a similar AgBrCl emulsion coated on a clear(no blue dye) support (see Example 2), it is estimated that the supportitself contributed about -10 to the measured b* values. Thus, the AgBrClemulsion itself actually provided a minus b* value contribution whilethe AgIBr emulsion provided a positive b* value contribution. Thedifference in b* values between the two emulsions was 3.8-3.9. Thisdemonstrates that the AgBrCl emulsion allows for a significant reductionin the blue density of the support (and hence neutral minimum density)while providing a cold image. From Tables I and II it is estimated thatwith the magnetic recording layer present the blue dye could be reducedto an extent sufficient to allow its b* contribution to be less than-5.0 while still achieving a cold (-6.5 or more negative) b* valueemploying the AgBrCl emulsion. The colder image tone contribution of theAgBrCl emulsion more than offsets the contribution of the warmer imagetone contribution of the magnetic recording layer. Hence, it is possibleto accommodate a magnetic recording layer while achieving cold imagetones or a better balance of colder image tones and lowered minimumdensities.

Example 2

A series of elements of the layer arrangement of Element I, describedabove, but with MRL replaced with IL-2, were provided. Differing silverhalide grain compositions were employed. The elements were constructedfor exposure using a helium-neon 670 nm laser.

FILM SUPPORT

The film support was a conventional clear (not blue tinted) 7 mil (177.8mm) transparent poly(ethylene terephthalate) radiographic film support.

PELLOID

The pelloid contained gelatin (25.1) and the antihalation dyesbis[3-methyl-1-(p-sulfophenyl)-2-pyrazolin-5-one-(4)]pentamethineoxonol(0.96) and 1,4-benzene sulfonic acid,2-[3-acetyl-4-{5-[3-acetyl-1-(2,5-disulfophenyl)-1,5-dihydro-5-oxo-4H-pyrazol-4-ylidene]-1,3-pentadienyl}-5-hydroxy-1H-pyrazol-1-yl]pentasodiumsalt (1.74).

SURFACE OVERCOATS

The surface overcoats contained gelatin (4.5), matte beads (0.2) andsilicone lubricant (0.14).

INTERLAYERS

The interlayers contained gelatin (4.5).

EMULSION LAYER

The emulsion layer contained an emulsion comprised of sulfur and goldsensitized silver halide cubic grains (20.2) optimally spectrallysensitized withanhydro-9-ethyl-3,3'-bis(3-sulfopropyl)-4,5,4,',5'-dibenzothiacarbocyaninehydroxide, sodium salt; gelation (21.8);4-hydroxy-6-methyl-2-methylmercapto-1,3,3A-tetraazaindene (3 g/Ag M);resorcinol (1.0) and sodium disulfocatechol (0.2). Grain sizes andsilver halide compositions are set out in Table I below.

All of the hydrophilic colloid layers were fully forehardened using 2.4wt % bis(vinylsulfonylmethyl)ether, based on the weight of gelatin.

Exposure and Processing

The elements were exposed using a helium-neon laser emitting at 670 nm.Processing was conducted using a Kodak X-OMAT 480 RA™ processor, usingthe processing cycle, developer and fixer, previously described.

Observations of covering power, image tone (reported in terms by b*values), and fixing time are summarized in Table II. The fixing time wastaken as the time required to lower residual silver to 1.1 mg/dm².

                  TABLE II                                                        ______________________________________                                                                         Image  Fixing                                       ECD     Silver Halide                                                                            Cov.   Tone   Time                                  Element                                                                              (μm) (mol. ratio)                                                                             Power  (b*)   (sec.)                                ______________________________________                                        E1     0.23    Br.sub.0.30 Cl.sub.0.70                                                                  18     -2.4   5.6                                   E2     0.24    I.sub.0.03 Br.sub.0.97                                                                   16     +1.7   17.7                                  E3     0.23    Br         18     +1.1   7                                     E4     0.23    Cl         13     -7.5   4                                     ______________________________________                                    

From Table II it is apparent that the coldest image tone and the fastestfixing time were realized by Element E4 containing a AgCl emulsion.Unfortunately, this emulsion exhibited the lowest covering power. E2 andE3 demonstrate the positions of AgIBr and AgBr emulsions, halidecompositions that are commonly employed in radiographic elements. TheAgIBr emulsion was clearly inferior in terms of covering power, imagetone and fixing time as compared to the AgBr emulsion. The AgBr emulsionexhibited a higher covering power as compared to the AgCl and AgIBremulsion, but was otherwise wise unremarkable, exhibiting a positive b*value image tone and a longer fixing time than the AgCl emulsion.

Taking all performance categories into account superior properties wererealized by Element E1 employing the AgBrCl emulsion. The AgBrClemulsion provided a relatively cold image tone and a low fixing timewhile covering power was equal to the highest observed level. To reach acold image tone (b* -6.5 or more negative) less blue density is requiredin the support of an element employing a AgBrCl emulsion and hence abetter relationship between image tone and minimum density can berealized.

Example 3

Variations of Elements 1E and 2E, described above, were constructedvarying the coating coverages of the silver halide (stated in mg/dm²silver) and, in some elements, adding an infrared opacifying dye atvaried coating coverages (stated in mg/dm²) to the pelloid layer.

The percent of a 942 nm gallium arsenide laser beam attenuated by thevarious unprocessed elements is shown in Table III.

                  TABLE III                                                       ______________________________________                                        Element   AgIBr   AgBrCl     IROD-1 % Atten.                                  ______________________________________                                        E5        0       0          0      11                                        E6        2.7     0          0      23                                        E7        5.4     0          0      32                                        E8        10.9    0          0      47                                        E9        21.8    0          0      59                                        E10       0       2.7        0      15                                        E11       0       5.4        0      18                                        E12       0       10.9       0      21                                        E13       0       21.8       0      23                                        E14       0       10.9       0.11   25                                        E15       0       10.9       0.22   42                                        E16       0       10.9       0.44   69                                        ______________________________________                                    

From Table III it should be noticed that 21.8 mg/dm² AgIBr, a fullyacceptable coating coverage level, is sufficient to exceed the 50percent attentuation level that is sought for the presence of a film tobe detected by a rapid access processor input IR sensor. On the otherhand, from the AgBrCl coating coverage series it is apparent that threesuccessive doublings of the silver coating coverage created only a veryslow increase in infrared attenuation. Hence, it is apparent that amaximum acceptable 40 mg/dm² silver coverage would have been exceededwell before attenuation reached an acceptable 50 percent level.

The coatings with successively higher levels of the infrared opacifyingdye show that even small increases in the levels of the dye markedlyincreased the percent attentuation. Thus, the deficiency of the AgBrClemulsion in attenuating infrared radiation can be readily overcome bythe addition of relatively low levels of infrared opacifying dye.

Example 4

Gelatin (32.7) was coated on a transparent poly(ethylene terephthalate)radiographic film support. The gelatin was hardened with 1 wt %bis(vinylsulfonylmethyl)ether. The gelatin contained varied amounts ofinfrared opacifying dye, shown in Table IV.

The transmittance of the film samples were determined by placing theunprocessed film between and in contact with an 942 nm gallium-arsenidelaser and an infrared detector of the type used as a input film detectorin a rapid access processor.

                  TABLE IV                                                        ______________________________________                                                              Percent                                                 Dye     Coverage (mg/dm.sup.2)                                                                      Transmittance                                                                              Color                                      ______________________________________                                        None    0             80           Clear                                      IROD-7  0.33          50           Clear                                      IROD-7  0.66          35           Clear                                      IROD-7  0.99          30           Sl. Blue                                   IROD-1  0.33          41           Clear                                      IROD-1  0.66           8           Sl. Blue                                   IROD-1  0.99           4           Blue                                       ______________________________________                                         Sl. = slightly (i.e., just noticeably)                                   

From Table IV it is apparent that IROD-1 and IROD-7 were both effectivein reducing infrared transmittance to levels below 50%. The bluecoloration imparted by dye addition was an advantage in that it can beused to impart the desired cold image tone to a processed element.IROD-1, a preferred infrared opacifying dye, reduced transmittance to agreater degree and produced a bluer tint at lower concentrations thanIROD-7.

When 942 nm radiation absorption of the coatings were measured beforeand after processing in a KODAK X-OMAT 480 RA™ rapid access processor asspecifically described above, no significant change in absorption wasmeasured. From this it was concluded by IROD-1 and IROD-7 both form apermanent part of the elements and are not removed to any significantextent during processing. Thus, each are capable of being detected bothby input and output IR sensors associated with the processor.

Example 5

A series of elements were constructed to demonstrate the speed increasesthat can be realized by incorporating a thiaalkylene bis(armmonium salt)in a film of the type contemplated by the invention.

A film support similar to that of Example 2 was employed. Onto the filmsupport was coated a gelatin layer (10.8), which in some instancescontained a development accelerator candidate compound (0.55),identified in Table V.

Over the gelatin layer was coated an emulsion layer comprised of gelatin(26.9) and sulfur and gold sensitized AgBr₀.30 Cl₀.70 (19.4) optimallyspectrally sensitized with anhydro-9-ethyl-3,3'-bis(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyanine hydroxide, sodium salt. The emulsioncontained cubic silver bromochloride grains having an average ECD of0.147 μm.

Over the emulsion layer was coated gelatin (6.5). All of the abovelayers were fully forehardened using 2.5 wt %bis(vinylsulfonylmethyl)ether, based on the weight of total gelatin.

The elements were identically exposed to red light using a Wratten 29™filter, which transmits light at wavelengths longer than 600 nm.Processing was conducted using the processing cycle, developer and fixerpreviously described for use with Kodak X-OMAT 480 RA™, except that inthis Example a Kodak X-OMAT M-6™ processor was employed. Speed wasmeasured at a density of 1.0. Speed is reported in relative log units(0.30 log E=30 relative log units, where E represents exposure inlux-seconds).

The results are summarized in Table V.

                  TABLE V                                                         ______________________________________                                        Addenda      Relative Speed                                                   ______________________________________                                        None         194                                                              C-1          194                                                              C-2          187                                                              C-3          174                                                              Q-1          212                                                              Q-2          215                                                              Q-3          214                                                              ______________________________________                                        C-1  N,N'-(1,10-decylene)bis(pyridinium) chloride;                            C-2  1,1'-[1,6-(2,5-dithiahexylene)]bis(carboxylic acid); and                 C-3  4,4'-[1,8-(3,6-dithiaoctylene)]bis(pyridine)                         

It is apparent from Table V that the thiaalkylene bis(ammonium salt)compounds Q-1, Q-2 and Q-3 increase speed by approximately a half stop(0.15 log E). The comparative compound C-1, which differs from athiaalkylene bis(ammonium salt) structure by the absence of divalentsulfur atoms, fails to produce any significant increase in speed. Thisdemonstrates that the divalent sulfur atoms are essential components ofthe compounds that act as development accelerators. Similarly,comparative compound C-2, which replaces the ammonio groups with carboxygroups, also fails to produce any significant increase in speed, therebydemonstrating that the ammonio groups are also essentail to obtainingdevelopment acceleration. Finally, comparative compound C-3, whichsubstitutes trivalent nitrogen for quaternized nitrogen, also fails toproduce a significant speed increase, thereby demonstrating thatquaternized nitrogen is essential to obtaining development acceleration.

Example 6

A series of elements were prepared and tested similarly as in Example 5,except that the emulsion contained cubic AgBr₀.30 Cl₀.70 grains having amean ECD of 0.22 μm. Further, instead of adding to a gelatin undercoat,the varied compound was added directly to the emulsion layer in theconcentration shown in Table VI.

The results are summarized in Table VI.

                  TABLE VI                                                        ______________________________________                                        Addenda       Relative Speed                                                  ______________________________________                                        None          220                                                             Q-1 (0.11)    226                                                             Q-1 (0.22)    229                                                             Q-1 (0.44)    232                                                             Q-2 (0.22)    230                                                             Q-3 (0.22)    228                                                             C-1 (0.11)    220                                                             C-1 (0.11)    220                                                             C-2 (0.22)    218                                                             C-3 (0.22)    197                                                             C-4 (0.22)    221                                                             C-5 (0.11)    215                                                             C-5 (0.22)    212                                                             C-5 (0.44)    204                                                             C-6 (0.22)    219                                                             C-7 (0.22)    220                                                             ______________________________________                                        C-4  N,N'-(1,10-decylene)bis(1-methylmorpholinium) p-toluene-                      sulfonate;                                                               C-5  1,10-dihydroxy-3,6-dithiaoctane;                                         C-6  N,N'-(1,6-hexylene)bis(trimethylammonium) chloride;                      C-7  N,N'-[1,8-(3,6-disulfooctane)bispyridinium methylsulfonate;          

The results shown in Table VI are consistent with the results reportedin Table V. This demonstrates that the thiaalkylene bis(ammonium salt)structure is required to achieve speed enhancement. The results areconfirmed at varied concentration levels, and it is demonstrated thatthe thialkylene bis(ammonium salt) produces similar results whetherplaced in the emulsion layer or a gelatin undercoat.

Example 7

Two series of films were constructed as described in Example 2, butusing the emulsions of Example 2, Element E1 and Example 5. Thedevelopment accelerator Q-4 was placed in the developer in theconcentrations shown in Table V. Red exposures were used as described inExample 5. Processing was conducted as in Example 2, except thatdevelopment time was extended to 30 seconds. Speed was again measured ata density of 1.0, as in Example 5.

The results are summarized in Table VII.

                  TABLE VII                                                       ______________________________________                                        ECD (μm)                                                                           Q-4 (mg/L) Dmin     Dmax   Relative Speed                             ______________________________________                                        0.23     0         0.10     4.21   270                                        0.23     50        0.10     4.23   278                                        0.23    200        0.16     4.19   293                                        0.23    400        0.26     4.15   307                                        0.147    0         0.05     4.06   233                                        0.147    50        0.06     4.07   239                                        0.147   200        0.08     3.98   251                                        0.147   400        0.19     3.90   263                                        ______________________________________                                    

It is demonstrated in Table VII that a large increase in speed isprovided by the thialkylene bis(ammonium salt) development acceleratorwith little impact on either maximum or minimum density levels.

Example 8

A series of elements were constructed to demonstrate the effect ofincorporated development accelerator and/or supplemental developingagent on observed levels of speed in elements containing an incorporateddeveloping agent.

A film support similar to that of Example 2 was employed. Onto the filmsupport was coated an emulsion layer comprised of gelatin (32.7) andsulfur and gold sensitized AgBr₀.30 Cl₀.70 (21.8) optimally spectrallysensitized withanhydro-9-ethyl-3,3'-bis(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyaninehydroxide, sodium salt. The emulsion contained cubic silverbromochloride grains having an average ECD of 0.23 μm. The developingagent HQ-1 or HQ-10 was incorporated in the emulsion layer in aconcentration of 0.5 equivalents (5.5 or 11.6 mg/dm², respectively). Asupplemental developing agent and development accelerator incorporationswere varied, as shown in Table VIII.

Over the emulsion layer was coated gelatin (6.5). All of the abovelayers were fully forehardened using 2.5 wt %bis(vinylsulfonylmethyl)ether, based on the weight of total gelatin.

The elements were identically exposed to red light using a Wratten 29™filter, which transmits light at wavelengths longer than 600 nm. Theelements were identically developed for 20 seconds at 35° C. using KodakRoyalprint™ activator, fixed for 30 seconds using the fixer compositionpreviously described, and then washed in water for 2 minutes.

The results using HQ-1 are summarized in Table VIII and the resultsusing HQ-10 are summarized in Table IX.

                  TABLE VIII                                                      ______________________________________                                        SDA-18   Q-1     Dmin      Dmax  Relative Speed                               ______________________________________                                        0        0       0.06      2.84  234                                          (0.22)   0       0.06      3.07  243                                          (0.22)   (0.11)  0.07      2.88  251                                          (0.22)   (0.22)  0.07      2.96  256                                          (0.44)   0       0.06      2.95  248                                          (0.44)   (0.11)  0.07      3.01  262                                          (0.44)   (0.22)  0.08      2.94  260                                          ______________________________________                                    

                  TABLE IX                                                        ______________________________________                                        SDA-18   Q-1     Dmin      Dmax  Relative Speed                               ______________________________________                                        0        0       0.06      1.53  132                                          0        (0.11)  0.06      1.82  165                                          0        (0.22)  0.06      2.18  182                                          0        (0.44)  0.06      2.57  187                                          (0.11)   0       0.06      2.63  187                                          (0.22)   0       0.06      3.04  196                                          (0.44)   0       0.06      3.20  211                                          (0.11)   (0.11)  0.06      2.88  206                                          (0.11)   (0.22)  0.06      3.17  206                                          (0.11)   (0.44)  0.07      3.36  223                                          (0.22)   (0.11)  0.06      3.07  207                                          (0.22)   (0.22)  0.06      3.17  219                                          (0.22)   (0.44)  0.06      3.39  227                                          (0.44)   (0.11)  0.07      3.27  210                                          (0.44)   (0.22)  0.08      3.26  217                                          (0.44)   (0.44)  0.10      3.48  236                                          ______________________________________                                    

From Tables VIII and IX it is apparent that each of supplementaldeveloping agent and development accelerator are capable of enhancingspeed, but the highest levels of speed are realized when both arepresent. All incorporation levels shown provided satisfactory imagingresults.

Example 9

Exposure and processing of separate samples of the same series ofelements shown in Table IX were repeated, except that instead of usingan activator solution Developer A was diluted to one quarter of itsoriginal strength.

The results are summarized in Table X.

                  TABLE X                                                         ______________________________________                                        SDA-18   Q-1     Dmin      Dmax  Relative Speed                               ______________________________________                                        0        0       0.06      3.37  223                                          0        (0.11)  0.06      3.36  232                                          0        (0.22)  0.06      3.42  230                                          0        (0.44)  0.06      3.31  235                                          (0.11)   0       0.06      3.38  223                                          (0.22)   0       0.06      3.44  222                                          (0.44)   0       0.06      3.37  222                                          (0.11)   (0.11)  0.06      3.33  231                                          (0.11)   (0.22)  0.06      3.42  231                                          (0.11)   (0.44)  0.07      3.33  238                                          (0.22)   (0.11)  0.06      3.41  229                                          (0.22)   (0.22)  0.07      3.40  230                                          (0.22)   (0.44)  0.07      3.31  236                                          (0.44)   (0.11)  0.06      3.43  228                                          (0.44)   (0.22)  0.06      3.43  231                                          (0.44)   (0.44)  0.07      3.13  244                                          ______________________________________                                    

When a film sample lacking both Q-1 and SDA-18 were processed using thestandard rapid access processing employed in Example 2, a relative speedof 223 was observed. From Table X it can be seen that the developmentaccelerator allowed recapture of the speed lost by diluting thedeveloper, whereas the supplemental developing agent had little impacton speed. Although the elements with higher speeds show preferredperformance characteristics, all of the elements tested exhibitedacceptable performance characteristics.

Example 10

The effect of incorporated developing agent on the physical propertiesof the film was ascertained by employing a film sample according toExample 9 containing no incorporated development accelerator orsupplemental developing agent. The developing agent HQ-10 wasincorporated at varied levels, as shown in Table XI.

                  TABLE XI                                                        ______________________________________                                        (mg/dm.sup.2)                                                                           Equivalents  Mushiness Tackiness                                    ______________________________________                                        0         0            121       3                                             (2.3)    0.125        122       3                                             (5.8)    0.25         108       3                                            (11.6)    0.5          103       3                                            (17.3)    0.75          99       10                                           (23.1)    1.0           82       10                                           ______________________________________                                    

Tackiness was measured on an arbitrary scale where a rating of 1indicates the film was not tacky and a rating of 10 indicates that thefilm blocks (adheres to another film placed in contact with it).Mushiness was measured in terms of the weight in grams applied that hadto be applied to a stylus to create a gauge (plow) in the film coating.Both tackiness and mushiness were within acceptable limits when thedevelopment agent was present in a concentration of 0.5 equivalent orless.

Example 11

An element according to the invention, E17, was constructed similarly asElement E1 (see Example 2), except that the mean grain ECD was 0.26 μm,the silver coverage was 21.4 mg/dm², and the emulsion layer containedQ-1 (0.05).

A control element, E18, was constructed similarly as element E17, exceptthat the emulsion was that employed in Element E2 (see Example 2).

Six hundred samples (each sample was a 14×17 inch, 35.6×43.2 cm, sheet)of each element were exposed and identically processed as in Example 2,but with replenishment of developer and fixer as described below.

Samples of element E18 were processed with standard replenishment ofdeveloper and fixer. That is, 60 mL of developer and 90 mL of fixer wasadded after each sheet was processed. The results are summarized inTable XII. Speed was measured at a density of 1.0. Dmax* is the densityobserved at an exposure of 1.1 log E greater than the exposure requiredto produce a density of 0.2 above Dmin.

                  TABLE XII                                                       ______________________________________                                        Sheet Processed                                                                           Dmin         Dmax*   Speed                                        ______________________________________                                        1st         0.18         3.75    293                                          300th       0.19         3.79    297                                          600th       0.19         3.73    296                                          Δ(1-600)                                                                            0.01         -0.02    3                                           ______________________________________                                    

The comparison of Table XII was next repeated, except that the developerand fixer replenishment were each reduced to 20 mL/sheet. The resultsare summarized in Table XIII.

                  TABLE XIII                                                      ______________________________________                                        Sheet Processed                                                                           Dmin         Dmax*   Speed                                        ______________________________________                                        1st         0.18         3.50    288                                          300th       0.18         2.84    282                                          600th       0.18         2.63    273                                          Δ(1-600)                                                                            0.01         -0.87   -15                                          ______________________________________                                    

A comparison of Tables XII and XIII reveals that reduced replenishmentresulted in significant loss of maximum density and speed.

The comparisons reported in Tables XII and XIII were repeated, exceptthat sheets of element E17 were substituted for sheets of element E18.The results with replenishment rates employed in Table XII are reportedin Table XIV, and the results with replenishment rates employed in TableXIII are reported in Table XV.

                  TABLE XIV                                                       ______________________________________                                        Sheet Processed                                                                           Dmin         Dmax*   Speed                                        ______________________________________                                        1st         0.20         4.10    295                                          300th       0.20         4.13    294                                          600th       0.20         4.08    294                                          Δ(1-600)                                                                            0.00         -0.02    -1                                          ______________________________________                                    

                  TABLE XV                                                        ______________________________________                                        Sheet Processed                                                                           Dmin         Dmax*   Speed                                        ______________________________________                                        1st         0.22         4.17    294                                          300th       0.21         4.13    296                                          600th       0.21         4.13    297                                          1200th      0.21         4.09    295                                          Δ(1-1200)                                                                           -0.01        -0.08    1                                           ______________________________________                                    

In comparing Tables XIV and XV it is apparent that element E17 of theinvention exhibited much less variance as a function of reducedreplenishment than the control element E18. Further, element E17 showedless variance in performance, even when processing was extended over1200 successive sheets of film with reduced replenishment. Thisdemonstrates the marked improvement of the elements of the invention.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What is claimed is:
 1. A radiation-sensitive silver halide film forreproducing digitally stored medical diagnostic images through a seriesof laterally offset exposures by a controlled radiation source followedby processing in 90 seconds or less, including development, fixing anddrying, comprised ofa transparent film support having front and backmajor faces, a front hydrophilic colloid layer unit containing anemulsion layer coated on the front face of the support, and a backhydrophilic colloid layer unit coated on the back face of thesupport,wherein (A) the film exhibits an average contrast in the rangeof from 1.5 to 2.0, measured over a density above fog of from 0.25 to2.0, (B) the emulsion layer(1) contains silver bromochloride grainsincluding grain faces lying in {100} crystal planes(a) comprised of from20 to 40 mole percent bromide, based on total silver, (b) having a meanequivalent circular diameter of less than 0.40 μm, (c) exhibiting anaverage aspect ratio of less than 1.3, and (d) coated at a silvercoverage of less than mg/dm², and (2) has adsorbed to the surfaces ofthe silver bromochloride grains at least one spectral sensitizing dyehaving an absorption half peak bandwidth in the spectral region ofexposure by the controlled radiation source, (C) the back hydrophiliccolloid layer unit contains a magnetic recording layer, and (D) the filmcontains an infrared opacifying dye that is capable of reducing speculartransmission through the film before, during and after processing toless than 50 percent, measured at a wavelength within the spectralregion of from 850 to 1100 nm.
 2. A film according to claim 1 whereinmagnetic recording layer is comprised of hydrophilic colloid andferromagnetic particles.
 3. A film according to claim 2 wherein theferromagnetic particles have a surface area of at least 30 m² /g, arecoated at coverage of from 0.1 to 10 mg/dm², and account for from 1 to10 percent of the total weight of the magnetic recording layer.
 4. Afilm according to claim 3 wherein the ferromagnetic particles have asurface area of at least 40 m² /g.
 5. A film according to claim 4wherein the ferromagnetic particles are γ-Fe₂ O₃ particles.
 6. A filmaccording to claim 3 wherein the ferromagnetic particles are coated at acoverage of from 0.2 to 0.7 mg/dm².
 7. A film according to claim 3wherein the ferromagnetic particles are acicular having an average majoraxis length of less than 0.3 μm a ratio of major axis length tothickness diameter of up to 5:1.
 8. A film according to claim 1 whereinthe support contains a blue dye and the b* value of the film is -6.5 ormore negative.
 9. A film according to claim 8 wherein the blue dyecontributes less than -5.0 to the b* value of the film.
 10. A filmaccording to claim 1 wherein the silver bromochloride grains are coatedat a coverage in the range of from 10 to 30 mg/dm², based on silver.